Electric antihunt servo system



Dec. 28, 1948. v J. P. TONER 2,457,330

ELECTRIC ANTIHUNT SERVO SYSTEM Original Filed Nov. 27, 1945 2Sheets-Sheet 1 FIGJ.

HIGH AND LOWSPEED RELAY INVENTOR. .JOHN P TONER H/S ATTORNEYS.

Dec. 28, 1948. T R 5 ELECTRIC ANTIHUNT SERVO SYSTEM Original Filed Nov.27, 1945 g Sheets-Sheet 2 I ht. II III HIS A TTORNETEYS.

known as "control transformer."

Patented Dec. 28, 1948 ELECTRIC ANTIHUNT SERVO SYSTEM John 1'; Toner,Woodhaven, N. Y., assignor to Arma Corporation, Brooklyn, N. Y., acorporation of New York Continuation oi application Serial No. 631,078,November 27, 1945. This application October 31, 1047,8eriai No. 783,801

This invention relates toservo systems, and has particular reference tosystems in which a low power variable is automatically reproduceddynamically as a high power motion with a minimum of error and'withouthunting or other unwanted oscillations.

This application is a continuation of my copending application SerialNo. 631,078, filed November 2'7, 1945, for Electric anti-hunt servosystem, now forfeited.

In modern electronic servo-control systems, the remote control issupplied by the well known method of self-synchronous transmission whichproduces a rotating magnetic signal in a receiver A null rotor coil is,kept balanced in this field in non-inductive angular position by theresponse from the servo motor, any voltage that'may be induced in therotor of the control transformer, due to error in reproduction, beingamplified electronically and used to drive the servo motor. Such asystem is, of course, subject to oscillation and therefore damping hasbeen supplied by feeding the output voltage from a linear generatordriven by the servo-motor and against the signal error voltage from thecontrol transformer, whereby the phase relations of the system arechanged and oscillation is accordingly prevented. However, such phasedamping results in a lag in response of the servo-motor, which is thencompensated by adding the output voltage of a second linear generator,likewise driven by the servo-motor, but through a spring and flywheelfilter unit, so that it acts only when changes in speed of responseerror occur. One form of such servo-control system is disclosed inco-pending application Serial No. 626,406, filed November 2, 1945, by F.W. Cunningham, now Patent No. 2,444,813, issued July 6, 1948.

In accordance with the present invention, an improvement in theabove-described servo-system is provided, which resides principally inthe replacement of the two generators and filter unit by a singlegenerator assembly serving the same purpose in a simple, novel andeffective manner. The new system comprises the major elements of theabove-described servo-system, but the servomotor drives the statorportion of the substitute generator which has a free low-inertia rotorcoupled to the stator through a suitable low-pass mechanical filterassembly, the rotor having no brushes to restrict its response. Thevoltage generated by the generator is fed into the servomotor driving adynamic error circuit in opposition to the error voltage to thereby dampthe oscillation tendency of the response.

It will be seen that a system of this invention will have no eflect onthe circuits so long as there is uniform speed of the servo-motor, andthat ideal damping efiects will be applied to the system 24 Claims. (CL318-30) 2 immediately upon a variation in speed. In this way theseparate damping arrangement of other systems are eliminated andcompactness, lightness and simplicity result.

For a more complete understanding of the invention, reference may be hadto the accompanying drawings, in which: I

Figure 1 is a diagram of a modern electronic servo-control system,including a self-damping preferred form of the damping generator whichoperates with the servo-control system of Fig. 1 according to thisinvention; and,

Figs. 3 and 4 illustrate modifications of the generator assembly of thisinvention.

Referring to Fig. 1, which illustrates a type of an electronic follow-upsystem to which the present invention is applicable, theself-synchronous signal or demand from the remote low and high speedtransmitters, not shown, arrives along the two groups of bus wires Inand I2, group I0 carrying the low speed signal and the group I2 carryingthe high speed signal. The three spacephased currents are supplied fromlow speed bus wires l0 by the jumpers l5 to the stator windings MS ofthe control transformer I4 and. produce a rotating magnetic field, theorientation of which represents the demand value at any instant.Likewise, Jumpers l'l supply high speed signal currents from high-speedbus wires l2 to stator windings IBS of the control transformer iii, toproduce in it a rotating field travelling in synchronism with therotating field S but much more rapidly, in order to give accuracy.

In the servo-control system under consideration, described in greaterdetail in said copending application, either one or the other of thecontrol transformers It or IE is in operation, depending uponsynchronism between the remote transmitter and servo-motor 25, which isenergized by error voltage induced in rotor winding HR or IBR, whicheveris connected thereto, and servomotor 25 then drives that rotor windingto noninductive relation to its stator, through gearing 24 and jackshaft 23 connected by gearin 2| to shafts I8 and I9 carrying respectiverotor windings MR and iGR. Shift from high to low speed control isautomatically made by the relay 20 and the error voltage output ofeither control transformer H or I6 is amplified in electronic ampliher Ito drive the servo-motor 25 as will be described, the structure ofthereiay being described in detail in said copending application.

The arrangement of the present invention in the above-describedservo-control system includes the mechanism designated 42 in Fig. 1,whose principal element is a specially constructed generator mounted forbodily rotation about its armature axis. Such rotation of generator 43is effected by servo-motor 25 connected thereto through gearing 24, Jackshaft 23, large gear 2i of the group 2| and gear 44 fixed on the casing01 generator 43,-in order that the generator 43 may rotate at all timesin synchronism with the servo-motor 25 and the rotor windings [4B andIBR 01' control transformers i4 and I6. Slip ring pairs 46 and 41 areprovided mounted on an insulating disc 45 secured on the end of thecasing of generator 43, as shown, the outer pair 48 receiving currentfrom corresponding brushes connected to alternating current source I3,as shown, while brushes engaging the inner pair 41 feed the currentgenerated in generator 43 in series opposition into the amplifiercircuit of servo-motor 25, as shown at 48.

As shown in Fig 2, the armature of generator 43 is free to rotate withinits casing and is controlled by the flywheel 49 and its associatedapparatus.

The casing of the generator 43 is provided with a re-entrant hub orcolumn 50, which carries bearings and 52, which are in turn carried onthe journal 53 firmly secured in the bracket 54, as by the nut 55, itbeing understood that the bracket 54 is firmly mounted on the frame ofthe servo system of Fig. 1. As shown, the stator assembly 56, 56a isfixed to the hub 50, so that these two stators rotate together as thegenerator 43 is rotated bodily on bearings 5i and 52 by means of theintegral gear 44 from the servo-motor 25, so that the stator system 56,56a will, at all times, rotate in synchronism with servo-motor 25.

Each stator 58 and 56a has its own windings and between them is formedthe air-gap 58 in which a thin, tubular armature shell 59 of conductingmaterial is adapted to rotate, as shown in Fig. 2, to generate thedamping currents. The outer stator 56a has its windings 60 suppliedthrough the slip-rings 45 with single-phase alternating current from theleads 1 3 as shown in Fig. 1, and hence there is set up in stator 56a apulsating field which itself has no direct effect on the stator windings6! of the stator 56, because these windings are purposely placed so thatthey have little or no mutual inductance. However, when the tubulararmature shell 59 is being driven, the currents inducted therein affectthe other stator 56, producing in its winding 6| a voltage proportionalto the speed of the armature shell 59 relatively to the stators 56 and56a. The armature shell 59 is mounted on short shaft 64 carryingflywheel 49 and Journalled on free bearings 62 and 63 supportedrespectively on the hub 50 and in the'end of the casing 51. By this arrangement, the generating means of the damping generator 43 is purelyinertia or acceleration controlled, i. e., when the servo-motor 25 isrunning uniformly, the flywheel 49 and shell armature 59 will be runningwith it and there will be no damping voltage generated because none isneeded. However, as soon as the servo-motor 25 speeds up or slows down,there will be damping voltage generated in winding 6i because theflywheel 49, due to its inertia, will cause-relative motion of the shell59 to the stator assemblies 56 and 56a.

Although freedom of response of armature shell 59 is desired, completefreedom is not eil'ective because of overrunning, so that viscous typecoupling is provided to control it. Such a coupling may include anextension 66 on shell 59 lying in a gap between a multi-polar ringpermanent magnet 65 and the continuous iron ring 61, both fastened inthe casing 51, as shown. Finally, the generated damping voltage is takenfrom stator winding Ii through slip rings 41 and applied in seriesopposition, as. shown in Fig. 1, to the driving circuit 48 of amplifier4 I.

In operation of the servo-system of this invention, as disclosed inFigs. 1 and 2, the remote low and high speed self-synchronoustransmitters, not shown, supply low speed signal and high speed signalto the bus wires I0 and I2, respectively. Being connected by wires i5 tolow speed bus wires i U, a rotating low speed signal field isestablished in stator winding 8 ct low speed control transformer i4, anda similar high speed rotating signal field is established in statorwinding |6S of high speed transformer 16 by reason of its connection bywires H to high speed bus wires l2. The error voltage induced in one ofthe respective rotor windings HR and IBR of transformers l4 and I 5 inresponse to the corresponding stator fields when the rotor windings arein inductive angular relation to their stator windings, is impressedupon servo-motor 25, after amplification at 41. Servo-motor 25 respondsto such error voltage to drive the active rotor winding through gearing2i and 24 toward null or non-inductive angular relation with itscorresponding stator winding, thus constantly striving to reduce theerror voltage to zero.

Which rotor winding, [4R or 1813 is active or effective to energizeservo-motor 25 under the circumstances described, depends upon relay 26,which swings control from respective low speed to high speed controltransformers I l and I6, as often as necessary to maintain synchronismbetween servo-motor 25 and the remote transmitter. Thus, when low speedcontrol transformer i4 is controllin servo-motor 25 and it is followingclosely, relay 20, in response to the low error voltage from transformerrotor winding MR, quickly shifts control to the high speed transformerl6 for greater accuracy of following. Conversely, should synchronism belost, such as when the apparatus is starting its operation, relay 2Ushifts control to low speed transformer i4, whose rotor Winding MR feedserror voltage to servo-motor which remains in operation only untilservomotor 25 is following the remote transmitter closely, when relay 2Dshifts to high speed control in the manner described, high speed controltransformer l6 thus bein in control the major part of the time. Theforegoing description of the operation of the servo-system illustratedin Fig. 1 and of relay 2!) is given as a basis for explaining theoperation of the improvements of the present invention, further detailsof the sytem and relay 20 being available by reference to said copendingapplication.

The generator 43 of unit 42 interposed in the servo-motor circuit, isrotated bodily by servomotor 25 through gearing 24, 21' and 44, thusrotating stators 56 and 56a, the alternating current-fed winding 60(Fig. 2) of the former setting up a pulsating field in air gap 58. Thistends to produce a voltage proportional to the speed of the servo-motor25. Then, as armature shell 59 rotates in response to the magnetic dragof magnet 65 on the armature extension 56, the flux across air-gap 58 isaltered by shell 59, so that the corresponding voltage induced in thewinding 6i oi the other stator 56 is reduced to a voltage proportionalto the speed of shell 59 relatively to the stators 56 and 56a. Thus,voltage generated in stator winding BI is picked up from innerslip-rings 41 and fed at 48 in opposition to the error voltage in thecircuit of servo-motor 25, to thereby accurately damp the same as soonas a speed variation occurs, thus eliminating a double set of generatorsas in the aforementioned prior system.

The operation of the system of this invention may be set forthmathematically as follows: If 01=displacement of generator stator 86, aand 1 1; its speed, 0z==displacement of generator armature shell 88 and1*: its speed, then If r=speed of armature shell I! relatively to stator58, Sim-then r=n-.rs, and if Ea =output damping voltage of generator 0,then Ea=0r,

' where C is a constant of proportionality. y

In the form shown in Fig. 2, the armature shell 58 is coupled tothestator assembly ll, "a only by the magnetic drag'due to magnet 85, sothat if Tr=-Torque due to magnetic drag. then Ti=Bir, where B1 is aconstant of proportion-.

ality.

IfIi represents the inertia of thewflywheel 48 and I: all other inertiain the armature shell 6!,

' from the rotor to the fixed structure Likewise if Bl=drag due tomagnet 65 and Ba=all other viscous drag and B=total drag -(neglectingall Coulomb friction) let. 4

With this idealized arrangement, the torque 'r acting on I is I iT=-8f=B(T1- 1'2) servo-motor 25 and the generator assembly 42, and,since r is sinusoidal, S=je,'

' l ams?- and the damping voltage,

1 01 E- C-fl- W4- Instead of effecting the magnetic drag from rotor tostator, as in Fig. 2, it may be effected of the mech- 6 anism. Suchmodification is illustrated in Fig. 3, wherein all common parts arenumbered the same as in Fig.2, the change being made at the left-handend. Thus, instead of supporting the magnet 85 and cooperating iron ring61 on the stator casing 51, they are supported on a bracket 69 securedto the frame 64, with the extension 88' cooperating with magnet 65 andring 61 being carried by the flywheel 49 instead of being mounteddirectly on the armature. Also, a spiral clockspring Bil-is connectedbetween the inertia flywheel 49 and the stator casing 51, as shown. Now,the spiral clock-spring 68 causes the armature shell 59 to turn and thusreduce the voltage induced in' the stator 58 by stator 56a, and thisvoltage is fed into the circuit of servo-motor 25 as described.Mathematically expressed, and if total drag (B), flywheel and armatureinertia (I) and the spring 68 constant (10- are the combined parameters,and Coulomb friction is again neglected, then-the torque acting on thearmature shell 59 is and the equation of motion is substituting in aboveISTg+BT3+i z but. since (2) IS-l-B a which is the damping voltage fromthe generator 43 of the modification of the invention shown in Fig. 3..In this case 13 must be large enough so that the coupling circuitcontaining the sprin 68 is itself critically damped.

Reierring to Fig. 4, like parts are again numberecl as in Figs. 2 and 3and the assembly is quite similar to that shown in Fig. 2 exceptthatclockspring 68' has been introduced between casing 51 7 and fivwheel 49,as shown, in addition to the magnetic drag device 65, 56, 61. TheOperation of the modification of Fig. 4 is in general similar In all ofthe modifications of the invention shown in Figs. 2 to 4, it will beobserved that the stator assembly of generator 43 of unit 42 rotateswith the servo-motor 25, being geared thereto, and that the dampingvoltage generated by the same is due to changing speed of theservo-motor 25 acting on the inertia masses used. Consequently, there isno lag produced in servo-motor response to the signal when following auniform signal, but the damping effect appears promptly whenacceleration appears in the servomotor 25. As will be seen, there are nobrushes on the armature shell 59 so that it responds in a' manneraccurately determined by the motion of the system and the mechanicalfilter, thereby providing the necessary damping control to theservo-system shown in Fig. 1.

It will also be observed that the damping voltage output of unit 42 willbe an increasing function of frequency, and that this function can beadjusted to be most suitable for any particular servo-motor by selectionof the appropriate circuit and choice of the individual parameters.Furthermore, the damping arrangement of this invention, when used withalternating current voltage, is not sensitive to large variations in thefrequency of the supply voltage, which is not true for damping systemswhich work on the error voltage. Also, the system of this invention issuperior to damping systems which work on the error voltage inapplications where the coupling between the servo-motor 25 andpositioning device, such as the control transformer I4 or i6, is loose,since the damping device 43 can be rigidly coupled to the servo-motor.

The system of this invention is superior to one using two generators, infeatures other than compactness and simplicity. In order to obtain highaccuracy for constant velocity signals in a system using two generators,the two separate generators must be accurately matched over the requiredspeed range. Also, this matching may have to be maintained for widevariations in (a) Ambient temperature, (1)) Magnitude of the appliedvoltage, (c) Frequency of the applied voltage.

Although several embodiments of this invention have been illustrated anddescribed herein, it is to be understood that the invention is notlimited thereby but is susceptible of changes in 8 form and detailwithin the scope of the appended claims.

I claim:

1. In an electromechanical servo-control system having a servo-motorenergized by the voltage generated in a transformer rotor' windingdriven by the servo-motor toward non-inductive angular relation in thefield of the transformer stator winding energized in accordance with themovements of a remote self-synchronous transmitting means, thecombination of a damping generator having rotable rotor and statormembers, driving connections between said servo-motor and said statormember, means responsive to changes in speed of said stator member fordriving said rotor member, and means mounted on said rotor member andcooperating with said stator member for supplying to said servo-motor avoltage that is a function of changes in the speed of said statormember, whereby the response of said servo-motor to the voltage inducedin said transformer rotor winding is modified by the voltage generatedin said damping generator.

2. In an electromechanical servo-control system having a servo-motorenergized by the voltage generated in a transformer rotor winding drivenby the servo-motor toward non-inductive angular relation in the field ofthe transformer stator winding energized in accordance with themovements of a remote self-synchronous transmitting means, thecombination of a damping generator having rotatable rotor and statormembers, driving connections between said servo-motor and said statormember, means responsive to changes in speed and in acceleration of saidstator member for driving said rotor member, and means mounted on. saidrotor member cooperating with said stator member for supplying to saidservo-motor a voltage that is a function of changes in the speed and inthe acceleration of said stator member, whereby the response of saidservo-motor to the voltage induced in said transformer rotor winding ismodified by the voltage generated in said damping generator.

3. In an electromechanical servo-control system having a servo-motorenergized by the voltage generated in a "transformer rotor' windingdriven by the servo-motor toward non-inductive angular relation in. thefield of the transformer stator winding energized in accordance with themovements of a remote self-synchronous transmitting means, thecombination of a damping generator having rotatable rotor and statormembers, driving connections between said servo-motor and said statormember, means responsive to changes in acceleration of said statormember for driving said rotor member, and means mounted on said rotormember. and cooperating with said stator member for supplying to saidservo-motor a voltage that is a function of changes in the accelerationof said stator member, whereby the response of said servo-motor to thevoltage induced in said transformer rotor winding is modified by thevoltage generated in said damping generator.

4. In an electromechanical servo-control system having a servo-motorenergized by the voltage generated ln a transformer rotor winding drivenby the servo-motor toward non-inductive angular relation in the field ofthe transformer stator winding energized in accordance with themovements of a remote self-synchronous trans- 'mitting means, thecombination of a damping generator, a rotatable stator thereforincluding armature rotatable'in field of said field a field winding anda generating winding in the field thereof, an alternating current sourceconnected to said field winding, driving connections between saidservo-motor, and said stator, an armature rotatable in the field of saidfield winding for modifying the fiux to which said.

generating winding responds, means responsive to changes in speed ofsaid statorfor driving said armature, and series opposition connectionsbetween said ge erating winding and the input circuit of saidservo-motor, whereby the error voltage induced insaid transformer rotorwinding is opposed by any voltage generated in said damping generator..v

5. In an electromechanical servo-control syswinding for modifying theflux to which said generating winding responds, viscous coupling meansloosely connecting said armature to said stator and responsive tochanges in speed of said stator'for driving said armature, andelectrical connections between said generating winding and the circuitof said servo-motor, whereby the response of said servo-motor to thevoltage induced in said transformer rotor winding is modified bythevoltage generated in said. damping generator. a

'8. In an electromechanical servo-control system havingaservo-motorenergized by the voltage tem having a servo-motor energized by thevoltage generated ,in a transformer rotor winding driven-by theservo-motor toward nonvinductive angular relation in the field of thetransformer statorwinding energized in accordance with the, movements ofa, remote self-synchronous transmitting means, the combination of a'damping generator, a rotatable stator therefor including a field windingand a generating winding in the field thereof, an alternating currentsource connected to said field winding, driving connections between saidservo-motor and said stator, an armature rotatable in the field of saidfield winding for modifying the flux to which said generating windingresponds, coupling means interposed between said armature and stator andresponsive to changes in speed of said stator for driving said armature,and electrical connections between said generating winding andthecircuit of said servo-motor, whereby the response of said servo-motor tothe voltage induced in said trans-- source connected to said fieldwinding, driving connections between said servo-motor and said stator,an armature rotatable in. the field of said field'winding for modifyingthe flux to which said generating winding responds, means responsive tochanges in speed of said stator for driving said armature, andelectrical connections between said generating winding'and the circuitof said servo-motor, vwhereby the responseof said generated in atransformer rotor winding driven by the servo motor-toward non-inductiveangular relation in the fieldof the transformer stator winding energizedin accordance with the movements of a remote self-synchronoustransmitting means, the combination of a damping generator,

a rotatable stator therefor including a field windingand a generatingwinding in the field thereof,

' an alternating current source connected to said field winding-drivingconnections between said servo-motor and said stator, an armaturerotatable in the field of said field winding for modifying the flux towhich said generating winding responds, magnetic coupling means on saidstator creating a magneticdrag on said armature inresponse to changes.in speed of said stator for driving said armature, and electricalconnections between said generating winding and the circuit of saidservo-motor, whereby the response of said servo-motor to the voltageinduced in said trans-. former rotor winding is modified by the voltagegeneratedin said "damping generator.

9. In an electromechanical servo-control system having a servo-motorenergized by the voltage generated in a transformer rotor winding driven"o vbythe servo-motor toward non-inductive angular relation in the fieldoi the-transformerstator winding energized-in accordance with themovements of a remote selfhronous transmitting means, the combfiadamping generator, a rotatable stator a, or including a field windingand a generatin inding in'the-field thereof,

' an alternating'cur tsource-oonnected to said 'field winding, drivingconnections een saidservo-motor and said stator, an arm re rotatable inthe field of said field windingsforimodifying the fiux to which saidgeneratingfwiriding responds, elastic means interposed between saidarmature and said stator and responsive to changes in speed of saidstator for driving-said armature, and electrical connections betweensaid generating winding and the circuit of said servoservo-motor to thevoltage induced in said trans-- Q former rotor winding is modified bythe voltage generated in said damping generator.

'7. In an electromechanical servo-control syshereby the response of saidservo-motor 1 induced in said transformer rotor winding is m ed-by thevoltage generated in said damping generator.

ssIO-Q-Iman electromechanical servo-control systemhaving a servo-motorenergized by the voltage generatedin' a transformer rotor winding temhaving a servo-motor energized by the voltage generated in a transformerrotor winding driven by the servo-motor'toward non-inductive angularrelation in the field of the transformer stator winding energized inaccordance with the movements of a remote self-synchronous trans--mitting means, the combination of a damping generator, a rotatablestator therefor including a field winding and a generating winding inthe field thereof, an alternating current source connected to said fieldwinding, driving connections driven by the servo-motor toward noninductive angular relation in the field of the transformer statorwinding energized in accordance with the movements of aremoteself-synchronous transmitting means, the combination of a dampinggenerator,.a rotatable stator therefor including a field winding and agenerating winding in the field thereof, an alternating current sourceconnected to said field winding, driving'connections between saidservo-motor and said stator, an

v armature rotatable in the field of said field windvbetween saidservo-motor and said stator, an, 7 ing modifying the flux to which saidn r- 11 Y ating winding responds, means responsive to changes in speedof said stator for driving said armature, means retarding motion of saidarmature, and electrical connections between said generating winding andthe circuit of said servornotor, whereby the response of saidservo-motor to the voltage induced in said transformer rotor winding ismodified by the voltage generated in said damping generator.

11. In an electromechanical servo-control system having a servo-motorenergized by the voltage generated in a transformer rotor winding drivenby the servo-motor toward non-inductive angular relation in the field ofthe transformer stator winding energized in accordance wlth' themovements of a remote self-synchronous transmitting means, thecombination of a damping generator, a rotatable stator thereforincluding a field winding and a generating winding in the field thereof,an alternating current source connected to said field winding, drivingconnections between said servo-motor and said stator, an armaturerotatable in the field of said field winding for modifying the flux towhich said generating winding responds, means responsive to changes inspeed of said stator for driving said armature, inertia means on saidarmature, and electrical connections between said generating winding andthe circuit of said servo-motor, whereby the response of saidservo-motor to the voltage induced in said transformer rotor winding ismodified by the voltage generated in said damping generator.

12. In an electromechanical servo-control system having a servo-motorenergized by the voltage generated in a transformer rotor winding drivenby the servo-motor toward non-inductive angular relation in the field ofthe transformer stator winding energized in accorance with the movementsof a remote self-synchronous transmitting means, the combination of adamping generator, a rotatable stator therefor including a field windingand a generating winding in the field thereof,

an alternating current source connected to said field winding, drivingconnections between said servo-motor and said stator, an armaturerotatable in the field of said field winding for modifying the flux towhich said generating winding respends, means responsive to changes inspeed of said stator for driving said armature, a fiywheel for saidarmature, and electrical connections between said generating winding andthe circuit of said servo-motor, whereby the response of saidservo-motor to the voltage induced in said transformer rotor winding ismodified by the voltage generated in said damping generator.

13. In an electromechanical servo-control system having a servo-motorenergized by the voltage generated in a transformer rotor winding drivenby the servo-motor toward non-inductive angular relation in the field ofthe transformer stator winding energized in accordance with themovements o a remote self-synchronous transmitting means, thecombination of a damping generator, a rotatable stator thereforincluding a field winding and a generating winding in the field thereof,an alternating current source connected to said field winding, drivingconnections between said servo-motor and said stator, an armaturerotatable in the field of said field winding for modifying the flux towhich said generating winding responds, a flywheel for said armature,means interposed between said flywheel and said state: and responsive tochanges in speed of said stator for driving said armature, andelectrical connections between said generating winding and the circuitof said servo-motor, whereby the response of said servo-motor to thevoltage induced in said transformer rotor winding is modified by thevoltage generated in said damping generator.

14. In an electromechanical servo-control sys. tem having a servo-motorenergized by the voltage generated in a transformer rotor winding drivenby the servo-motor toward non-inductive angular relation in the field ofthe transformer stator winding energized in accordance with themovements of a remote self-synchronous transmitting means, thecombination of a damping generator, a rotatable stator thereforincluding a field winding and a generating winding in the field thereof,an alternating current source connected to said field winding, drivingconnections between said servo-motor and said stator, an armaturerotatable in the field of said field wind ing for modifying the flux towhich said generating winding responds, a flywheel for said armature,elastic means interposed between said fiywheel and said stator andresponsive to changes in speed of said stator for driving said armature,and electrical connections between said generating winding and thecircuit of said servo-motor, whereby the response of said servo-mot0r tothe voltage induced in said transformer rotor winding is modified by thevoltage generated in said damping generator.

15. In an electromechanical servo-control system having a servo-motorenergized by the voltage generated in a transformer rotor winding drivenby the servo-motor toward non-inductive angular relation in the field ofthe transformer stator winding energized in accordance with themovements of a remote self-synchronous transmitting means, thecombination of a damping generator, a rotatable stator thereforincluding a field winding and a generating winding in the field thereof,analternating current source connected to said field winding, drivingconnections between said servo-motor and said stator, an armaturerotatable in the field of said field winding for modifying the fiux towhich said generating winding responds, a flywheel for said armature,magnetic drag means interposed between said flywheel and said stator andresponsive to changes in speed of said stator for driving said armature,and electrical connections between said generating winding and thecircuit of said servo-motor, whereby the response of said servomotor tothe voltage induced in said transformer rotor winding is modified by thevoltage generated in said damping generator.

16. In an electromechanical servo-control system having a servo-motorenergized by the voltage generated in a transformer rotor winding drivenby the servo-motor toward non-inductive angular relation in the field ofthe transformer stator winding energized in accordance with themovements of a remote self-synchronous transmitting means, thecombination of a damping generator, a rotatable stator thereforincluding a field winding and a generating winding in the field thereof,an alternating current source connected to said field winding, drivingconnections between said servo-motor and said stator, an armaturerotatable in the field of said field winding for modifying the flux towhich said generating winding responds, a flywheel for said armature,means responsive to changes in speed of said stator for driving saidarmature, an elastic coupling between said flywheel and said stator, andelectrical connections between said generata ing winding and the circuitof said servo-motor,

whereby the response of said servo-motor to the voltage induced in saidtransformer rotor winding is modified by the voltage generated in saiddamping generator.

17. In an electromechanical servo-control system having a servo-motorenergized by the voltage generated in a transformer rotor winding inspeed of said stator for driving said armature, magnetic drag meansinterposed between a fixed part of said generator and said flywheel forretarding rotation of said flywheel, and electrical connections betweensaid generating winding and the circuit of said servo-motor, whereby theresponse of said servo-motor to the voltage induced in said transformerrotor winding is modidriven by the servo-motor towardnon-inductiveangular relation in the field of the transformer stator windingenergized in accordance with the movements of a remote self-synchronoustransmitting means, the combination of a damping magnetic drag means forsaid flywheel, and electrical connections between said generatingwinding and the circuit of said servo-motor, whereby the response ofsaid servo-motor to the voltage induced in said transformer rotorwinding. is modified by the voltage generated in said damping generator.

18. In an electromechanical servo-controlsystem having a servo-motorenergized by thevoltage generated in a transformer rotor winding drivenby the servo-motor toward non-inductive angular relation in the field ofthe transformer stator winding energized in accordance with themovements of a, remote self-synchronous transmitting means, thecombination of a damping generator, a rotatable stator thereforincluding a field winding and a generating winding in the field thereof,an alternating current source connected to said field winding, drivingconnections between said servo-motor and said stator, an armaturerotatable in the field of said field-winding for modifying the flux towhich said generating winding responds, coupling means connecting saidarmature to said stator and responsive to changes in speed of saidstator for driving said armature, a flywheel for said armature, magneticdrag means for said flywheel, and electrical connections between saidgenerating winding and the circuit of said servo-motor, whereby theresponse of said servo-motor to the voltage induced in said transformerrotor winding is modified by the voltage generated in said damp inggenerator.

19. In an electromechanical servo-control system having a servo-motorenergized by the voltage generated in a transformer rotor winding drivenby the servo-motor toward non-inductive angular relation in the field ofthe transformer stator winding energized in accordance with themovements of a remote self-synchronous transmitting means, thecombination of a damping generator, a rotatable stator thereforincluding a field winding and a generating V winding in the fieldthereof, an alternating current source connected to said field winding,driving connections between "said servo-motor and said stator, anarmature rotatable in the field of said field winding for modifying theflux to which said generating winding responds, a flywheel for saidarmature, elastic means interposed between said flywheel and said statorand responsive to changes fied by the voltage generated in said dampinggenerator.

20. In an electromechanical servo-control system adapted to be actuatedin accordance with the movements of remote self-synchronous transmittingmeans, the combination of a transformer having a stator windingenergized by said transmitting means and a rotor winding inductivelycoupled to said stator, winding, a servo-motor electrically connected tosaid rotor winding for energization in accordance with the voltage in-'1 duced therein, driving connections between said servo-motor and saidrotor whereby the latter is driven by said servo-motor to non-inductiverelation with said stator, a generator having a rotatable statorincluding a field winding and a generating winding, connections betweensaid field winding and an alternating current source, drivingconnections between said servo-motor and said generator stator, anarmature interposed between the field and generating windings of saidsaid stator for driving said armature, and electrical connectionsbetween said generating winding and the circuit of said servo-motor.

21. In an electromechanical servo-control system adapted to be actuatedin accordance with the movements of remote self-synchronous transmittingmeans, the combination of a transformer having a stator windingenergized by said transmitting means and a rotor winding inductivelycoupled to said stator winding, a servo-motor electrically connected tosaid rotor winding for energization in accordance with the voltageinduced therein, driving connections between said servo-motor and saidrotor whereby the latter is driven by said servo-motor to non-inductiverelation with said stator, a generator having a rotatable statorincluding a field winding and a generating winding, connections betweensaid -field winding and an alternating current source, drivingconnections between said servo-motor and said generator stator, anarmature interposed between the field and generating windings of saidstator, means responsive to changes in speed and in acceleration of saidstator for driving said armature, and electrical connections betweensaid generating winding and the circuit of said servomotor.

22. In an electromechanical servo-control system adapted to be actuatedin accordance with the movements of remote self-synchronous transmittingmeans, the combination of a transformer having a stator windingenergized by said transmitting means and a rotor winding inductivelycoupled to said stator winding, a servo-motor electrically connected tosaid rotor winding for energization in accordance with the voltageinduced therein, driving connections between said servo-motor and saidrotor whereby the latter is driven by said servo-motor to non-inductiverelation with said stator, a generator having a rotatable statorincluding a field winding and a generating winding, connections betweensaid field winding and an alternating current source, drivingconnections between said servo-motor and said generator stator, anarmature interposed between the field and generating windings of saidstator. means responsive to changes in acceleration of said stator fordriving said armature, and electrical connections between saidgenerating winding and the circuit of said servo-motor.

23. In an electromechanical servo-control system adapted to be actuatedin accordance with the movements or remote self-synchronous transmittingmeans, the combination of a transformer having a stator windingenergized by said transmitting means and a rotor winding inductivelycoupled to said stator winding, a servo-motor electrically connected tosaid rotor winding (or energization in accordance with the voltageinduced therein, driving connectionsbetween said servomotor and saidrotor whereby the latter is driven by said servo-motor to non-inductiverelation with said stator. a damping generator having a stator windingdriven by said servo-motor and including a generating winding, anarmature for said generator, an elastic coupling interposed between saidarmature and said stator whereby the latter drives the former inresponse to changes in speed of the stator, and opposed electricalconnections between the output of said generating winding and the inputof said servo-motor.

24. In an electromechanical servo-control system adapted to be actuatedin accordance with the movements of remote self-synchronous transmittingmeans, the combination or a transformer having a stator windingenergized by said transmitting means and a rotor winding inductivelycoupled to said stator winding. a servo-motor e1ec tricaily connected tosaid, rotor winding for energization in accordance with the voltageinduced therein, driving connections between said servogeneratingwindings or said stator, viscous cou-' pling means responsive to changesin speed or said stator for driving said armature, and series oppositionelectrical connections between said generating winding and the circuitof said servomotor.

JOHN P. TONER.

No references cited.

Certificate of Correction Patent No. 2,457,330. December 28, 1948.

JOHN P. TONER It is hereby certified that error appears in the printedspecification of the above numbered patent requiring correction asfollows:

Column 7, line 22, Equation 3, for that portion of the factor Where thesubnotation following dB is illegible, read 016,

and that the said Letters Patent should be read with this correctiontherein that the same may conform to the record of the case in thePatent Office.

Signed and sealed this 24th day of May, A. D. 1949.

THOMAS F. MURPHY,

Assistant Oommz'ssz'oner of Patents.

Certificate of Correction Patent No. 2,457,330. December 28, 1948.

JOHN P. TONER It is hereby certified that error appears in the printedspecification of the above numbered patent requiring correction asfollows:

Column 7, line 22, Equation 3, for that portion of the factor Where thesubnotation following d0 is illegible, read dB,,,;

and that the said Letters Patent should be read with this correctiontherein that the same may conform to the record of the case in thePatent Ofiice.

Signed and sealed this 24th day of May, A. D. 1949.

THOMAS F. MURPHY,

Assistant Commissioner of Patents.

